Heat engine

ABSTRACT

A heat engine has a first heat exchanger which is configured as a heater, has a second heat exchanger which is configured as a cooler, has a turbine which is arranged between the first and the second heat exchanger, and has a line system which has a working medium, is configured as a circuit and connects the components to one another in a fluidically conducting manner. If the first heat exchanger, the turbine and the second heat exchanger are arranged so as to follow one another in the vertical direction in the installed position, the heat engine can be designed as a particularly compact structural unit.

The invention relates to a heat engine having the characteristics of the preamble of claim 1.

A heat engine is known from WO 2012 028 149 A1, which uses a liquid fluid, such as, for example, carbon dioxide or coolant, such as R134A or R245A, as a working medium. In this connection, the temperature expansion of the liquid fluid, in each instance, is used as the fundamental principle of the heat engine, in order to recover mechanically usable work from heat energy, by means of acceleration of the gas. In this connection, the heat engine has a heater that heats and expands the liquid fluid, in each instance, so that the heated and expanded liquid fluid can rise up in a riser and can drive a flow engine disposed after the heater. A cooler is disposed to follow in the piping circuit of the heat engine, which cooler cools the liquid fluid, so that it can flow down a sink line disposed after the cooler, which line flows into the heater, and is conducted back to the heater. In order to prevent the liquid fluid from making a transition to the vapor state, a pressure regulation unit is installed in the circuit, which prevents evaporation of the liquid fluid.

A heat engine is described in WO 2011 040 828 A1, which has at least two spaces that stand perpendicular. The air is heated in one of the spaces, for example by means of electricity, so that it rises in the space, while it is cooled in the other space and flows down in it. The two spaces are connected with one another in fluidically conductive manner, both at the top and at the bottom. A flow engine is affixed at the head side of the space that heats the air, which engine is put into motion by the rising air and thereby converts thermal energy to mechanically usable work.

A heat engine having a first heat exchanger configured as a heater and a second heat exchanger configured as a cooler is known from U.S. Pat. No. 3,375,664 A, wherein a turbine is disposed between the first and the second heat exchanger. The heat engine also comprises a piping system having a fluid and configured as a circuit, which system connects the two heat exchangers with one another in fluidically conductive manner.

The heat engine described in DE 27 46 731 converts a liquid to the vapor state by means of solar collectors; this vapor is passed into a container filled with liquid, in which a blade turbine is mounted, wherein the turbine is driven by the vapor that flows in. The vapor is condensed, at least in part, by means of a condenser, and passed back to the solar collectors, so that the latter can evaporate the liquid once again.

Heat engines that are based on the evaporation of liquids are characterized in that they are configured with a complicated design and are generally suitable for use of greater temperature differences. It is true that there are also applications for the low-temperature range, for example based on the Organic Rankine Cycle, which are furthermore suitable for lower temperature differences, but in this embodiment, as well, a condenser must be provided as a heat sink, so that the fluid converted to the gas state or vapor state can be converted back to the liquid physical state. Furthermore, increased demands must be made on the tightness of the circuit, which is generally a closed circuit, particularly in the case of corresponding working media, so that as a result of this, as well, such a heat engine has a complicated design and is cost-intensive to produce.

It is true that liquid-based heat engines, which are based on thermal expansion of liquid working media, are easier to design, but particularly in the case of closed circuits and/or when using organic working media such as R134A, for example, increased demands must also be met by the tightness of the circuit. Furthermore, in this case pressure regulation must be provided, which prevent the working fluid from passing over to the gaseous state, because no condenser is provided in this system and conversion of the working fluid to the gaseous state makes the process become practically unmanageable.

Heat engines that are based on thermal expansion of gases have a clearly higher heat expansion of the working medium as compared with the liquid-based embodiments, and can be used at very slight temperature gradients. Thus, there is currently an increasing need for gas-conducted heat engines, which are based on the temperature-expansion principle and thereby bring about acceleration of the gas at the same pressure, and which are cost-advantageous, simple in design, and demonstrate great operational reliability at low maintenance. Furthermore, it is desirable that the system is easy to operate, and is characterized by a broad range of use.

The present invention concerns itself with the problem of indicating a new and improved or at least alternative embodiment for a heat engine, which is particularly characterized by simplicity of design, great operational reliability, and a large range of use.

[A 01] In one aspect of the invention, a heat engine having a first heat exchanger configured as a heater, having a second heat exchanger configured as a cooler, having a turbine disposed between the first heat exchanger and the second heat exchanger, and having a piping system having a gaseous working medium and configured as a circuit, which system connects the components with one another in fluidically conductive manner, is proposed, in which engine, in the installation position, the first heat exchanger, the turbine, and the second heat exchanger are preferably disposed in a vertical sequence.

[A 02] It is advantageous that proven components, such as, for example, the heat exchangers or the turbine, can be used in such an embodiment, which components can be made available on the market in any desired number and grade, with a managed design, for one thing, and are characterized, for another thing, by great freedom from maintenance and design simplicity. A compact construction is possible with such components, wherein setup and assembly of such a heat engine are simplified. Furthermore, such a heat engine can be used, for one thing, in the low-temperature range, at temperatures below 90° C., for example, and for another, it is suitable for converting slight temperature differences to mechanically or electrically usable work. It is also conceivable that the heat engine is conceived for a low-temperature range below 80° C., particularly below 70° C., if necessary below 60° C., and, for example, below 50° C. This low temperature allows the use of plastics, which demonstrates great mechanical strength and low heat losses in the case of corresponding fill materials. Furthermore, such a heat engine can be scaled almost in any desired manner with regard to its size and power, specifically in cost-advantageous manner and without further design effort.

In this connection, the gaseous working medium is heated in the first heat exchanger, configured as a heater, causing it to be expanded and accelerated because of its heat expansion. This kinetic energy of the gas is converted by the turbine, at least in part, to mechanically or electrically usable energy, while the subsequent second heat exchanger, configured as a cooler, converts the gaseous working medium back to the state, particularly with regard to temperature, that prevailed ahead of the first heat exchanger, in the flow direction of the gaseous working medium. Thus, essentially the same pressure prevails in the entire circuit, so that the entire process is carried out in isobar manner, and merely the kinetic energy or the dynamic pressure of the gaseous working medium is converted, at least in part, to mechanically or electrically usable energy.

Heat exchangers are understood to be components or modules through which a further working medium flows, wherein a heat transfer takes place between the further working medium and the gaseous working medium of the circuit. The piping system, configured as a circuit, is essentially any desired arrangement and sequence of hollow components that are connected with one another fluidically, in such a manner that the gaseous working medium can flow through them without significant friction losses.

Installation position is understood to be the arrangement of the heat engine in which it can be operated. This is a setup in the vertical direction. In this connection, a vertical direction is understood to be a perpendicular direction or a direction that is oriented essentially parallel to and opposite the effect of gravity. Because of such a vertical sequence of the first heat exchanger, the turbine, and the second heat exchanger counter to the direction of gravity, the heat engine furthermore also utilizes a chimney effect. In this connection, the gaseous working medium heated in the first heat exchanger is driven upward because of its lift, while the cooled, gaseous working medium wants to sink downward in the piping system at the tip of the heat engine and after the last heat exchanger, configured as a cooler. This chimney effect additionally supports circulation of the gaseous working medium during operation. As a result, a particularly compact construction is obtained, which can, however, also be used horizontally, for example, independent of position.

In this connection, the piping system that follows the last heat exchanger, configured as a cooler, is configured to be descending, particularly vertically, so that the cooled, gaseous working medium can flow downward without any noteworthy friction, following gravity, and can thereby support the chimney effect.

[A 02] If the first heat exchanger, the second heat exchanger, and the turbine are configured as an integral unit, the flow conditions in such an integral unit can be optimized and fixed, so that disadvantageous flow conditions with high friction resistances cannot occur in the heat engine, neither when such a system is being set up nor when its position is changed. Therefore great operational reliability and operational efficiency are ensured on the basis of the integral construction. Furthermore, because of the compact unit, setup of such a system is simplified and can accordingly be performed even by non-experts. In this connection, it is particularly possible to do without the piping between the individual components of the integral unit, so that the components are directly connected with one another in fluidically conductive manner.

If the turbine furthermore has a generator with which it is configured as an integral unit, the heat engine can advantageously be used for generating electrical energy, without an additional generator having to be connected with the heat engine or its turbine. Because of this integrated construction, the operational reliability is increased once again, and the installation of such a heat engine is furthermore simplified. Possible losses between turbine and generator can be minimized by means of such an integral construction, so that the components are optimally coordinated with one another.

[A 03] If the turbine is configured as a radial turbine, then a further working range can be covered by it, without complicated changes of the blade geometry, by means of changing the speed of rotation. This allows an efficient yield of electrically or mechanically usable energy from the turbine, even at only slight flow, because the flow velocity of the gaseous working medium, among other things, can be adapted by means of the speed of rotation.

[A 04] In advantageous manner, a blower or a diffuser can be disposed in the piping system, between the second heat exchanger and the first heat exchanger. The heat engine can be started up from a shut-down state, for example, by means of the blower or the diffuser, or the blower can also maintain the air circulation in the desired flow direction in the piping system or the further components of the heat engine, in supporting manner. In this connection, the mechanical energy applied to the gaseous working medium by way of the blower, at least in part, can be recovered by way of the turbine.

[A 05] Furthermore, a third, regulatable heat exchanger, particularly configured as a cooler, can be provided in the piping system, which exchanger is disposed after the second heat exchanger, following it vertically in the installation position. It is advantageous that a precisely defined state of the gaseous working medium can be adjusted, after the third, regulatable heat exchanger, by means of such a regulatable heat exchanger. If the second heat exchanger is accordingly not able to adjust this desired state in the gaseous working medium, this state can be achieved to a precise point by means of the third, regulatable heat exchanger. In this connection, it is also conceivable that the third heat exchanger is not configured as a cooler, but rather as a cooler and heater, so that excessive cooling of the air can also be offset by the third, regulatable heat exchanger. Such a regulatable heat exchanger accordingly increases process reliability and sets a defined and desired state, at least at one point, in the heat engine.

In this connection, it is also conceivable that in the case of temperature variations in the first heat exchanger, the third heat exchanger regulates for a constant temperature gradient. If the temperature in the first heat exchanger drops, accordingly, a final temperature can be set by the third heat exchanger, which temperature keeps the temperature difference between a hot region of the gaseous working medium before it flows into the turbine and a cold region of the gaseous working medium ahead of the first heat exchanger and/or after the last heat exchanger, configured as a cooler, constant. If, in this connection, the temperature in the first heat exchanger increases, then less cooling might have to take place, so that the regulatable third heat exchanger has to extract less thermal energy from the gaseous working medium.

[A 06] If air, helium, neon, argon, nitrogen, oxygen, carbon dioxide or any desired mixture of the aforementioned gases is used as the gaseous working medium, a particularly cost-advantageous gas/gas mixture, which is present and can be obtained in a sufficient amount, can be used as the gaseous working medium. In this connection, it is advantageous if no increased demands are made on the gas-tightness of the heat engine, either, because of the environmental compatibility of these gases, so that also with regard to the gas-tightness of the heat engine, the latter can be configured with a simpler design. Particularly in the case of air, the heat engine does not even have to be filled with the corresponding gaseous medium from a tank, in advance, but rather can be equipped with the gaseous working medium directly on site, while the system is being set up.

[A 07] If a constant excess pressure of 3-20 bar is set in the circuit, then a mass flow increase can be achieved on the basis of the excess pressure, which increase improves the performance density at the turbine. Furthermore, in this case a pressure regulation unit can also be provided, which unit ensures the constancy of this excess pressure, where any pressure variations that might occur can be offset by an excess-pressure vessel, for example. In this connection, it is also conceivable that a constant excess pressure of 3-15 bar, for example of 4-10 bar, possibly of 4-8 bar, and particularly of 5-7 bar is set. An excess pressure of 6 bar is preferred.

Furthermore, a temperature gradient of maximally 50° C. can occur between a hot region of the circuit, directly ahead of the turbine, and a cold region of the circuit, directly after the last heat exchanger, configured as a cooler. Thermal energy can be advantageously converted to mechanically or electrically usable energy by means of such a slight temperature gradient, in which other heat engines can no longer be used. Accordingly, the usability of the heat engine is clearly increased or expanded, above all at low temperature gradients. In this connection, it is conceivable that the temperature gradient amounts to maximally 40° C., particularly maximally 30° C., and, if necessary, maximally 25° C.

Furthermore, if the heat engine is configured for the low-temperature range, it can be used at low temperatures, such as, for example, maximally 45° C., particularly maximally 40° C., and, if necessary, maximally 35° C., and thermal energy can be converted to mechanically or electrically usable energy.

[A 08] In a further aspect of the invention, a cascade of at least two heat engines, as described above, is proposed, in which the discharged thermal energy of the heat exchanger(s) configured as (a) cooler(s), of a preceding heat exchanger, in the cascade direction, is passed, at least in part, to the heat exchanger configured as a heater, of a heat engine that follows in the cascade direction. It is advantageous that a great temperature range or a great temperature gradient can also be utilized by means of such a cascade, by means of at least partial conversion of the thermal energy to mechanically or electrically usable energy. In this connection, the gaseous working medium used in the respective heat engine can be adapted to the respective temperature range, as can the dimensioning of the heat exchangers and of the respective turbine. In this connection, the cascade direction is understood to be the direction in which the heat energy is transferred, between the individual heat engines, to the one that follows, in each instance.

[A 09] The efficiency of the heat engine can also be advantageously increased further if a heat recovery unit is provided between a turbine forward flow and a turbine return flow of the working medium.

In a further aspect of the invention, the use of a heat engine, as described above, having at least one of the following heat sources is proposed:

[A 10] If, for example, the fluid of a district heating system is used as the heat source, then the waste gas stream of the cogeneration power plant, for example, can be used as a heat source, and the waste gas heat itself can be converted, at least in part, to mechanically or electrically usable energy. However, it is also conceivable that the heating fluid of the district heating system is used as a heat source, for example directly on location in the cogeneration power plant or at any desired location in the district heating line or on location at the end customer of the district heat. Thus, for example, electrical energy can be generated from the heat of the district heating line at any desired location of the district heating line, so that separate power lines are not required at this location. This is also conceivable for use at the end consumer, so that electrically usable energy is generated from the district heat at the end consumer location, which energy can be supplied alternatively or in addition to the household power supply. Such a use is also conceivable in the case of a fluid of a home heating system, for example the waste gas stream of a home boiler/furnace system or the heating fluid of the central heating system, as well as in the case of the fluids of solar heating systems. Fundamentally, any type of waste heat can be used.

Furthermore, fluids such as a waste gas stream, for example, of an internal combustion engine or of a fuel cell can also be used for further utilization of the waste heat, for example, in order to increase the energy efficiency of the systems. Chemical reactors, for example, can also be used as heat sources, as can fluids in the steel industry, such as, for example, the waste gas stream in a steel mill, which is to be purified and furthermore possesses a high temperature. Stored heat can also serve as a heat source, for example heat stored in a hot-water tank, as in the case of solar collectors, or using paraffins, salts, etc. as a heat storage medium.

[A 11] It is advantageous if the heat exchanger of the heat engine is configured as a spiral-shaped pipe system that has a connection pipe at its center, which pipe connects an outgoing spiral with an incoming spiral. In this way, the heat exchanger has a very compact structure, thereby taking up only very little space in a heat engine.

[A 12] The pipe system of the heat exchanger is preferably structured as a double pipe consisting of an inner pipe and an outer pipe, wherein the gaseous working medium flows through the inner pipe and a liquid medium flows through the outer pipe, and wherein the inner pipe has a gas displacer in the region of an end of the pipe system where an outlet for the gaseous working medium and an outlet for the liquid medium are situated. The gas displacer is disposed in the inner pipe in such a manner that the inner pipe is artificially narrowed in the direction of the end of the pipe system, so that a constant mass stream prevails in the inner pipe. As a result, both heat discharge and heat feed take place in isobar manner.

The figures show, schematically, in each instance:

FIG. 1 a schematic representation of a heat engine,

FIG. 2 a cascade composed of multiple heat engines,

FIG. 3 a heat engine having a heat recovery unit,

FIG. 4 a heat exchanger of the heat engine according to FIG. 1,

FIG. 5 a section A-A through the heat exchanger according to FIG. 4, and

FIG. 6 a detail of the heat exchanger according to FIG. 4, along the section line B-B.

A heat engine 100, as shown in FIG. 1, has a first heat exchanger 120 configured as a heater, a turbine 130, and a second heat exchanger 140 configured as a cooler, following one another in the vertical direction. This arrangement of the first heat exchanger 120, the turbine 130, and the second heat exchanger 140 has a gaseous working medium flowing through it in the desired flow direction 150. A piping system 160 is fluidically conductive with the first heat exchanger 120, the turbine 130, and the second heat exchanger 140, wherein the piping system 160, together with the first heat exchanger 120, the turbine 130, and the second heat exchanger 140, is configured as a circuit 170. In FIG. 1, an installation position 180 of the heat engine 100 is shown, in which the heat engine 100 is usually operated. In this connection, the vertical direction 110 is essentially disposed parallel to the direction of gravity, and oriented counter to the effect of gravity, so that the inflow of the piping system 160 into the first heat exchanger 120 represents the lowest point and the outflow out of the second heat exchanger represents the highest point of the heat engine 100.

The first heat exchanger 120, the turbine 130, and the second heat exchanger 140 can form an integral unit, as shown in FIG. 1, so that handling of the heat engine during setup of the system, as well as during maintenance or relocation of the system is advantageously facilitated.

Furthermore, the heat engine 100 can be equipped with a blower 190 disposed in the piping system 160, which transports the air in the desired flow direction 150. This blower 190 can be used to support the flow of the gaseous working medium in the desired flow direction or for starting up the heat engine. At least a part of the energy supplied to the gaseous working medium by means of the blower 190 can be recovered by means of the turbine 130.

The heat engine 100 can be equipped with a third heat exchanger 200, which is disposed to follow the second heat exchanger 140 in the circuit 170, in the vertical direction 110. This third heat exchanger can be configured to be regulatable, so that a desired temperature T₁ of a cold region 210 of the heat engine can be set at the outlet of the third heat exchanger. In this connection, a hot region 220 just ahead of the entry into the turbine 130 has a temperature T₂, so that the temperature T₂ of the hot region 220 and the temperature T₁ of the cold region 210 have a defined temperature gradient ΔT.

Such heat engines 100 can build up a cascade 230, as shown in FIG. 2, where in the cascade direction 240, the heat q of a preceding heat exchanger 100′, 100″ taken from the second heat exchanger 140 is supplied to the first heat exchanger 120 of a heat engine 100″, 100′″ that follows in the cascade direction 240, as supplied heat Q. In this way, a greater temperature gradient can be utilized by means of such a cascade of heat engines 100′, 100″, 100′″, because the temperature gradients ΔT of the individual heat engines can be summed up to form a total temperature gradient ΔT_(G).

A variant of the heat engine according to the invention, having a counter-current heat exchanger 250, is shown in FIG. 3. Heat q_(r) is used for pre-heating the working medium ahead of the second heat exchanger 140, for heat recovery in counter-current heat exchanger 250, so that the efficiency of the entire engine increases. The engine therefore develops less waste heat. The working medium, which has already been pre-cooled in counter-current heat exchanger 250, is cooled down further to the starting state in heat exchanger 140. The pre-heated working medium is heated up again in heat exchanger 120, for entry into turbine 130, after it has passed through the diffuser or the blower 190.

FIG. 4 shows the heat exchanger 120 according to FIG. 1, where the inner workings of the heat exchanger 120 can be seen. The heat exchanger 120 is as a spiral-shaped pipe system 304, which is configured as a double spiral, wherein the pipe system 304 possesses a connection pipe 305 in its center, which pipe connects an incoming spiral 301 with an outgoing spiral 302. Because of the spiral-shaped structure of the pipe system 304, multiple pipe sections 308 to 310 that lie next to one another, i.e. pipe coils, can be seen. In this connection, the pipe system 304 is configured as a double pipe, which comprises an inner pipe 312 that is surrounded by an outer pipe 313. In this connection, the gaseous working medium flows through the inner pipe 312, and a liquid medium, preferably water, flows through the outer pipe 313. Air, helium, neon, argon, nitrogen, oxygen, carbon dioxide or any desired mixture of the aforementioned gases is used as the gaseous working medium, wherein a constant excess pressure of 3-20 bar is set in the inner pipe 312. This is therefore an isobar heat exchanger 120. Because the other heat exchangers of the heat engine 1 (see FIG. 1) are also isobar heat exchangers, both the energy supply and the energy supply proceed in isobar manner. In this connection, the energy supply takes place by means of supplying heat, and the energy discharge takes place by way of discharging heat, as well as by way of an equal-pressure turbine, i.e. mechanical work.

The pipe system 304 has a first end 306 at the outgoing spiral 302 and a second end 307 at the incoming spiral 301, wherein an inlet (not shown) for the liquid medium is provided at the first end 306, and an outlet (not shown) for the liquid medium is provided at the second end 307. The pipe system 304 is connected with a blower, not shown, with which the gaseous working medium is moved through the inner pipe 312 of the pipe system 304. This blower ensures that the gaseous working medium is moved in a predetermined direction, and thereby the movement of the gaseous working medium is independent of convection. A diffuser can also be used instead of a blower.

At the first end 306, there is an inlet for the gaseous working medium (not shown), and at the second end 307, there is the outlet for the gaseous working medium (not shown), with the pipe section 308 being the last pipe coil.

It is understood that the other two heat exchangers 140 and 200 of the heat engine 100 according to FIG. 1 can also be structured as a spiral-shaped pipe system.

It is also clear to a person skilled in the art that the pipe system 304 does not have to be configured as a double pipe.

FIG. 5 shows a detail of the heat exchanger 120 according to FIG. 4 along the section line A-A. The pipe section 308 consists of an inner pipe 312 that is surrounded by the outer pipe 313. A heating medium outlet 311 is affixed to the pipe section 308. A liquid heating medium, preferably water, is guided out of the outer tube 313 by way of this heating medium outlet 311. This heating medium heats the gaseous working medium, while the latter flows through the pipe system 304. A heating medium displacer 314 is provided in the outer tube 313. It is guaranteed, by means of the heating medium displacer 314, that the heating medium and the gaseous working medium demonstrate heat exchange surfaces of the same size. The gaseous working medium, which was heated up in the heat exchanger 120, flows through the inner pipe 312. A gas displacer 315 is provided in the inner pipe 312, which displacer artificially narrows the pipe cross-section of the inner pipe 312. This gas displacer 315 guarantees that the flow velocity of the gaseous working medium in the pipe system 304 increases at a constant mass stream.

FIG. 6 shows a detail of the heat exchanger 120 according to FIG. 4 along the section line B-B. The inner pipe 312 having the gas displacer 315 can be seen, wherein the inner pipe 312 is surrounded by the outer pipe 313. A heating medium feed line 316 is provided on the outer pipe 313, through which the heating medium flows, through which feed line the heating medium gets into the outer pipe 313 of the pipe system 304. The heating medium displacer 314 can also be seen in the outer pipe 313. The heating medium flows in the direction of the end 306 and heats the gaseous working medium, which flows opposite to the heating medium in the inner pipe 312, while doing so.

As can be seen in FIGS. 5 and 6, the gas displacer 315 takes up an increasingly greater region in the inner pipe 312, the closer the pipe system 304 is situated relative to the end 306. This is due to the fact that the gaseous working medium has a higher temperature in the end 306 of the pipe system 304 and therefore a lower density as well as a higher flow velocity than in the region of the end 307, because there, the gaseous working medium to be heated up is conducted into the pipe system 304. Therefore it is guaranteed, by means of the gas displacer 315, that the mass stream of the gaseous working medium remains constant in the pipe system 304.

REFERENCE SYMBOL LIST

-   100, 100′, 100″, 100′″ heat engine -   110 vertical direction -   120 first heat exchanger -   130 turbine -   140 second heat exchanger -   150 flow direction -   160 piping system -   170 circuit -   180 installation position -   190 blower, diffuser -   200 third heat exchanger -   210 cold region -   220 hot region -   230 cascade -   240 cascade direction -   250 counter-flow heat exchanger for heat recovery (air pre-heater) -   301 outgoing spiral -   302 incoming spiral -   306 end -   307 end -   308 pipe section -   309 pipe section -   310 pipe section -   311 heating medium outlet -   312 inner pipe -   313 outer pipe -   314 heating medium displacer -   315 gas displacer -   316 heating medium feed line -   T₁ temperature of the cold region -   T₂ temperature of the hot region -   ΔT temperature gradient -   ΔT_(G) total temperature gradient -   Q supplied heat -   q discharged heat -   q_(r) recovered heat -   E, W recovered, usable electrical energy or mechanical work 

1. Heat engine having a first heat exchanger (120) configured as a heater, having a second heat exchanger (140) configured as a cooler, having a turbine (130) disposed between the first and the second heat exchanger, and having a piping system (160) having a gaseous working medium and configured as a circuit (170), which system connects the components (120, 130, 140, 190, 200) with one another in fluidically conductive manner, wherein in the installation position (180), the first heat exchanger (120), the turbine (130), and the second heat exchanger (140) are preferably disposed in a sequence in the vertical direction (110).
 2. Heat engine according to claim 1, wherein the heat exchangers (120, 140, 200) are configured as an integral unit with the turbine (130) and/or wherein the turbine (130) has a generator with which it is configured as an integral unit.
 3. Heat engine according to claim 1, wherein the turbine (130) is configured as a radial turbine and has an adaptation for the speed of rotation, if applicable.
 4. Heat engine according to claim 1, wherein a blower (190) or diffuser (190) is disposed in the piping system (160), between the second heat exchanger (140) and the first heat exchanger (120).
 5. Heat engine according to claim 1, wherein a third, preferably regulatable heat exchanger (200), particularly configured as a cooler, is provided in the piping system (160), which exchanger is disposed vertically following the second heat exchanger (140), in the case of vertical installation, in the installation position (180).
 6. Heat engine according to claim 1, wherein air, helium, neon, argon, nitrogen, oxygen, carbon dioxide or any desired mixture of the aforementioned gases is used as the gaseous working medium, and/or wherein a constant excess pressure of 3-20 bar is set in the circuit (170).
 7. Heat engine according to claim 1, wherein a temperature gradient (ΔT) of maximally 70° C. occurs between a hot region (220, T₂) of the circuit (170), directly ahead of the turbine (130), in the case of vertical installation in the vertical direction (110), and a cold region (210, T₁) of the circuit (170) having a vertical direction (110), directly after the last heat exchanger (140, 200), configured as a cooler.
 8. Cascade composed of at least two heat engines (100′, 100″, 100′″) according to claim 1, wherein the discharged thermal energy (q) of the heat exchanger(s) (140, 200) configured as (a) cooler(s), of a preceding heat engine (100′ 100″), in the cascade direction (240), is passed, at least in part, to the first heat exchanger (120), configured as a heater, of a heat engine (100″, 100′″) that follows in the cascade direction (240).
 9. Heat engine according to claim 1, wherein a heat recovery unit (250) is provided between a turbine forward flow and a turbine return flow of the working medium.
 10. Use of a heat engine according to claim 1, having at least one of the following heat sources: a fluid of a district heating system, a fluid of a home heating system, a fluid of a solar heating system, a fluid of an internal combustion engine, a fluid of a fuel cell, a heat source of a chemical reactor, a fluid in the steel industry, a fluid of a heat storage unit.
 11. Heat engine according to claim 1, wherein the heat exchanger (120, 140, 200) is configured as a spiral-shaped pipe system (304), which has a connection pipe (305) in its center, which pipe connects an outgoing spiral (302) with an incoming spiral (301).
 12. Heat engine according to claim 11, wherein the pipe system (304) is configured as a double pipe having an inner pipe (312) as well as an outer pipe (313), wherein the gaseous working medium flows through the inner pipe (312) and a liquid medium flows through the outer pipe (313), and wherein a gas displacer (315) is provided in the inner pipe (312), which displacer artificially narrows the pipe cross-section of the inner pipe (312). 